An organic electroluminescence (referred to herein as organic EL) display device is arranged with a light-emitting element in each pixel and displays an image by individually controlling the emitted light. A light-emitting element includes a structure in which a layer (referred to herein as [light emitting layer]) including an organic EL material is sandwiched between a pair of electrodes distinguished as an anode and cathode. When electrons are injected from the cathode and holes are injected from the anode, the electrons and hole recombine in the light emitting layer. In this way, light emitting molecules within the light emitting layer are excited by the discharge of surplus energy and following this light is emitted due to de-excitation.
In the organic EL display device, an anode in each light emitting element is arranged as a pixel electrode in each pixel and a cathode is arranged as a common electrode which bridges a plurality of pixels and is applied with a common voltage. The organic EL display device controls the emitted light by applying the voltage of the pixel electrode to each pixel with respect to the voltage of the common electrode.
In recent years, high definition of organic EL display devices is progressing. When pixels are simply miniaturized in order to achieve high definition, the area of a contact hole part arranged in each pixel can no longer be ignored and a problem of arises where it is difficult to keep high aperture ratio. Furthermore, pixel circuits which must be arranged within a single pixel also receive the limitations of transistor numbers and design size due to a reduction in area.
In order to solve these problems, a method is disclosed in Japanese Laid Open Patent Publication No. 2012-018386 for example, in which contact holes and drive transistors are shared by making an anode electrode common between a plurality of sub-pixels, and driving by a field sequential method.
In such a display device, the anode electrode is made common between a plurality of light emitting elements and the cathode is divided and driven. In a manufacturing process of a divided cathode type display device, the cathode is formed by an evaporation method and the like using a mask. However, when the structure of a pixel in a display device becomes miniature and complex, it becomes difficult to form fine slits using one mask. Thus, when a plurality of masks is used, there is a possibility that yield may drop due to the alignment precision of each mask. As a result, there was a limit to achieving high-luminosity and high definition even in a divided cathode type display device.